1. Field of the Invention
The present invention relates generally to a method of calibrating a robot, and more particularly to a method of calibrating a robot, which can perform calibration by the movement of a robot itself without requiring an additional calibration device.
2. Description of the Prior Art
Generally, if machineries or tools requiring precise position control, such as robots, are disassembled and reassembled for repair or change of parts, offset of the initial positions of moving parts, such as robot arms, which may be varied relative to their previous positions, can frequently occur.
Therefore, if the offset occurs due to the change of parts, etc., previous calibration data must be revised by performing calibration to correct the offset.
In the prior art, if parts of a robot are changed and the correction of offset is required, calibration is performed by using an exclusive calibration jig, or on the basis of a calibration mark indicated on the body of the robot.
FIG. 1 is a control flowchart of a conventional method of calibrating a robot using a calibration jig.
As shown in FIG. 1, an original working tool attached to the body of the robot is detached therefrom at step S10, and an exclusive calibration tool is attached to the body of the robot at step S11. If the exclusive calibration tool is attached to the body of the robot, calibration is performed using the exclusive calibration tool at step S12.
At step S13, calibration data are obtained using calibration results from the performance of the calibration at step S12. Prestored previous calibration data are revised using the calibration data obtained at step S13 so as to correct the offset at step S14.
If the calibration data are revised, the exclusive calibration tool is detached from the body of the robot at step S15. Thereafter, the original working tool is attached again to the body of the robot at step S16.
As described above, the conventional method using the calibration jig is problematic in that it requires high precision of the calibration jig, and a calibrating operation is very complicated and requires much time, because an operation of changing the original working tool and the exclusive calibration tool must be performed twice. Further, the conventional method is troublesome in that if an actual user performs the calibration personally, the user must retain the exclusive calibration jig.
Meanwhile, in the conventional method of performing calibration on the basis of the calibration mark indicated on the body of the robot, calibration data are revised using the current position of the robot, after moving the mark indicated on the robot body to a position where a reference mark is indicated to enable the marks to coincide with each other.
Such a conventional method using the reference mark does not have the inconvenience that tools must be attached or detached to/from the body of the robot; however, the conventional method using the reference mark is problematic in that precision of calibration is relatively low.